Larry Karr, president of SCA Data Systems Inc. in Santa Monica, said he was hired on by Microsoft to assist the SPOT engineers. Karr said he was contacted by Bill Mitchell, a Microsoft engineer, about working on the technology, and helped design the FM subcarrier chipset being manufactured by National Semiconductor. The chipset consists of a front-end processor which receives the FM signal, and then passes it to a back-end microcontroller.

“We were the only game in town,” Karr said.

FM subcarrier transmission was originally brought about as a result of the Reagan administration, which deregulated the FM subcarrier radio spectrum in 1983 for non-commerical FM stations. Subcarriers transmit on normal FM spectra  88 to 108 MHz, VHF  and typically broadcast signals around 50 miles or so, depending upon atmospheric effects and other interference.

Traditionally, the most notable subcarrier customer has been Muzak, which has piped its dreamy background music on frequencies like 956.2875 MHz in Southern California. Today, Muzak uses a mix of satellite and other transmission methods to transmit its information to its customers.

Although FM radio blankets the U.S., Microsoft will have to create a network of FM broadcasters, perhaps one or two in most major markets, Karr said. SPOT’s range will be pretty much governed by the FM signal  once the “stereo” light goes out, the flow of data will stop, Karr said.

“The trick is that one of the really important things in the subcarrier signal has to be very good FM radio,” Karr said. “As part of SPOT, we’ve built an absolutely superb FM radio into a wristwatch. I don’t know if anybody will listen to one as a radio, but it’s there.”

The Atari connection

In 1984, according to Karr, video game maker Atari was about to go bust. It was a tumultuous year for Atari; Warner Communications, which at that time owned the company, eventually sold a controlling share of the company to Jack Tramiel, the deposed president of Commodore Computers. Atari dumped its nascent videophone operations onto a Japanese firm, and Warner sliced off Atari’s arcade division.

On the other hand, Atari engineers were busy trying to develop new ways to link humans and computers. Perhaps the most outrageous idea was the Atari Mindlink, which tried to develop an interface called “bioelectronics”. Mindlink tried to interpret muscle movement in a user’s forehead to control on-screen game sprites, but users apparently complained the devices were quite literally a headache to use.

About this time, Atari asked SCA’s Karr to design an alternative method of distributing games. The answer? FM subcarrier transmission, the pre-Internet’s broadband technology. Karr said FM subcarrier transmission could transmit up to 12 Kbits/s per radio station, and that the technology could be multiplexed to increase bandwidth further. New 2,400-baud (2.4-Kbit/s) modems, meanwhile, cost over $500.

“At the time, they had a problem with their video games,” Karr said of Warner. “Sometimes they produced a hit, and sometimes they’d produce landfill.”

The Karr/Atari prototype was a massive cartridge that plugged into the Atari 2600’s game slot. Inside, a jumble of passive components did what today small semiconductors do: received the FM signal, downloaded the game, and stored it inside the cartridge for playback. Field trials were successful, Karr said.

“In that case, every radio station would need to lease some space,” Karr said. A schedule could be distributed either on special dial-up phone lines or broadcast; “then you’d wait for the game loop, say, number 11, and the console would turn on automatically,” Karr said. “It worked; you’d take the joystick, push ‘fire’, up would pop the version and the thing would appear.”

Unfortunately, the device never appeared; soon after, a “Supercharger” tape player was created, which could store Atari games on tape, much like the Commodore PET.

Transmitting Atari 2600 games over the airwaves would have been a snap compared to today’s file sizes. A typical Atari 2600 game contained just 4 Kbytes of data, although ROMs could be expanded up to 32 Kbytes and higher through bank switching.

To compare, try saving a new file with the words “Hi there” in Microsoft Word 2002. “That’s 20 Kbytes, five times the amount of (ROM) space developers had to work with in the 2600,” said Chris Larkin, a developer who’s still writing games for the console.

Karr said Microsoft hasn’t asked him to work on a portable game player, but he’s working with the software giant on other projects that he’s legally forbidden from discussing. But he loves his SPOT watch, naturally.

“It’s a real kick,” Karr said. “I’ve got one of these watches. It’s amazing to walk down the street with a watch in data monitoring mode. Data’s coming in all from sides, and everything’s happy. I’m happy to see it all work smoothly.”

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